I've found mixed answers on this previously, but I have used it

We deploy Group Policy via Zen 6.5SP1b to Win2k and WinXP machines. The
policies used by these two platforms are very similar, so I create one
master policy using XPSP2, save, and then copy the policy folder files
(ADM, etc) into the respective platform's policy folders. It works
great, is much easier to manage in terms of consistancy, and the 2000
machines just ignore any settings that pertain only to XP.

Is anyone aware of any problem with this I am not seeing?